Simulation of Droplet Formation and Spread in Direct Ceramic Inkjet Printing

Recently, drop on demand inkjet printers have been used to deposit ceramic containing inks to develop ceramic components for several strategic applications (for sensors, fuel cells and for intelligent inks to be used as self assembling particles to interact with incident wave forms). It seems that the availability of literature with respect to the studies on fluid-structure interaction in a drop on demand inkjet printer is limited, though enough information is available on the preparation of ceramic inks. The design of nozzle for drop on demand inkjet printing involves transient interaction between fluids and structures to eject ink droplets. Study of phenomena that contribute to the droplet formation, ejection and deposition on a substrate for several combination of physical properties of constituents of the ink and the characteristics of actuation mechanism is relevant for understanding and effective utilization of direct ceramic inkjet printing (DCIJP). This paper focuses on the simulation of formation and ejection of a ceramic ink droplet (paraffin wax loaded with different volume fraction of alumina particles) from a reservoir using piezoelectric actuation. The properties of ceramic ink are found in literature and they are used for simulation. Simulations were performed with computational fluid dynamics software (CFD-ACE+) which can solve multi-physiscs problems as encountered in DCIJP. This study gives details of the tight interaction among different physical phenomena that contribute to he droplet formation and ejection process. The results from this study will be useful for the preparation of ceramic inks to achieve desired droplet characteristics.